{
let obj:{
    name:string,
    age:number,
    gender:string,
    // sayHi:(content:string)=>void
    sayHi(content:string):void
}={
    name:'李华',
    age:18,
    gender:'男',
    sayHi(content){
        console.log('你好'+content)
    }
}
obj.sayHi('---')

// 传统
if(obj.gender){
    obj.gender.concat()
}
// 优雅
obj.gender.concat()

// 可选练操作符
obj.gender?.concat()
// axios({
//     url:'',
//     method:'get',
//     data:{}
// })
}